DataGridViewCell.FormattedValueType (Propiedad)

private void UpdateLabelText()
{
    int WithdrawalTotal = 0;
    int DepositTotal = 0;
    int SelectedCellTotal = 0;
    int counter;

    // Iterate through all the rows and sum up the appropriate columns.
    for (counter = 0; counter < (DataGridView1.Rows.Count);
        counter++)
    {
        if (DataGridView1.Rows[counter].Cells["Withdrawals"].Value
            != null)
        {
            if (DataGridView1.Rows[counter].
                Cells["Withdrawals"].Value.ToString().Length != 0)
            {
                WithdrawalTotal += int.Parse(DataGridView1.Rows[counter].
                    Cells["Withdrawals"].Value.ToString());
            }
        }

        if (DataGridView1.Rows[counter].Cells["Deposits"].Value != null)
        {
            if (DataGridView1.Rows[counter]
                .Cells["Deposits"].Value.ToString().Length != 0)
            {
                DepositTotal += int.Parse(DataGridView1.Rows[counter]
                    .Cells["Deposits"].Value.ToString());
            }
        }
    }

    // Iterate through the SelectedCells collection and sum up the values.
    for (counter = 0;
        counter < (DataGridView1.SelectedCells.Count); counter++)
    {
        if (DataGridView1.SelectedCells[counter].FormattedValueType ==
            Type.GetType("System.String"))
        {
            string value = null;

            // If the cell contains a value that has not been commited,
            // use the modified value.
            if (DataGridView1.IsCurrentCellDirty == true)
            {

                value = DataGridView1.SelectedCells[counter]
                    .EditedFormattedValue.ToString();
            }
            else
            {
                value = DataGridView1.SelectedCells[counter]
                    .FormattedValue.ToString();
            }
            if (value != null)
            {
                // Ignore cells in the Description column.
                if (DataGridView1.SelectedCells[counter].ColumnIndex !=
                    DataGridView1.Columns["Description"].Index)
                {
                    if (value.Length != 0)
                    {
                        SelectedCellTotal += int.Parse(value);
                    }
                }
            }
        }
    }

    // Set the labels to reflect the current state of the DataGridView.
    Label1.Text = "Withdrawals Total: " + WithdrawalTotal.ToString();
    Label2.Text = "Deposits Total: " + DepositTotal.ToString();
    Label3.Text = "Selected Cells Total: " + SelectedCellTotal.ToString();
    Label4.Text = "Total entries: " + DataGridView1.RowCount.ToString();
}